Newswise — April 20, 2023--

A fresh investigation by scholars from Columbia University Mailman School of Public Health indicates that elevated urinary arsenic is associated with higher water arsenic levels for individuals who utilize both private wells and public water systems in the United States. The discoveries have been released in the Environmental Research journal.

Sustained exposure to arsenic, even at moderate or low levels, can escalate the probability of cancer and other persistent ailments. Although drinking water and dietary intake are significant sources of arsenic for the general public, the extent to which drinking water contributes to overall arsenic exposure in U.S. communities, particularly at levels less than those found in high concentrations in public water systems, has not been well-established.

By utilizing urinary arsenic biomarkers, the researchers assessed the correlation between arsenic levels in private wells and public water systems among U.S. communities. "Thus far, no comprehensive nationwide study had investigated the relationship between urinary arsenic biomarkers and drinking water arsenic levels to determine the contribution of drinking water to overall arsenic exposure in both regulated community water systems (CWS) and unregulated private wells," stated Maya Spaur, a doctoral candidate in environmental health sciences at Columbia Mailman School of Public Health.

The Agency for Toxic Substances and Disease Registry, a division of the U.S. Department of Health and Human Services, recognizes arsenic as a potent carcinogen and toxic substance that contributes to several negative health outcomes. As a result, it is listed as the number one substance on their priority list. The U.S. Environmental Protection Agency (EPA) is responsible for regulating the presence of arsenic in public drinking water systems and establishing the maximum contaminant level (MCL) allowed. Nonetheless, variations in arsenic concentrations continue to exist among community water systems throughout the United States.

The EPA lowered the maximum allowable contaminant levels to 10 µg/L from 50 µg/L in 2006. However, based on health risks alone, the EPA established an MCL goal (MCLG) of 0 µg/L. Along with community water systems, around 40 million individuals in the United States depend on private wells for their drinking water, making arsenic exposure from drinking water a major concern. However, private wells are not subject to federal regulations such as the EPA's MCL.

The study was conducted by assessing 11,088 participants from the 2003-2014 National Health and Nutrition Examination Survey (NHANES). The researchers assigned arsenic levels in private wells and community water systems to each participant based on their county of residence, using estimates previously calculated by the U.S. Environmental Protection Agency and U.S. Geological Survey. In addition, participants underwent an in-person interview, dietary recall, and physical examination.

On average, the recalibrated urinary dimethylarsinate (rDMA), the primary metabolite of arsenic excreted in urine, was 2.52 µg/L among individuals who relied on private wells and 2.64 µg/L among those who used CWS. Participants residing in the West and South regions and those of Mexican American, other Hispanic, and non-Hispanic other ethnicities had the highest levels of urinary rDMA. Furthermore, urinary rDMA concentrations were 25 percent and 20 percent higher among individuals with the highest third of CWS and private well arsenic levels, respectively, compared to those in the lowest third of the population distribution.

Maya Spaur commented, "Our study revealed a correlation between higher urinary arsenic levels among NHANES participants and higher arsenic levels in private wells and public water." She added that the researchers found very similar associations between urinary and water arsenic levels in both regulated public water systems and unregulated private wells, with the strongest associations observed in the South and West regions and among Mexican American participants. The study's findings suggest that water arsenic, including in public water systems, is a significant contributor to the total amount of arsenic measured in urine. Spaur emphasized the need for additional measures to address higher arsenic exposure in certain regions and communities.

Anne E. Nigra, the senior author and assistant professor of environmental health sciences at Columbia Mailman School of Public Health, emphasized the importance of assessing the correlation between drinking water arsenic and arsenic levels among U.S. populations. She stated that this information is crucial for developing effective drinking water regulatory policies and identifying communities that require further financial, technical, and regulatory assistance to minimize their residents' exposure to arsenic.

The co-authors of the study include Melissa Lombard and Joseph Ayotte from the U.S. Geological Survey, New England Water Science Center, Benjamin Bostick and Steven Chillrud from the Lamont-Doherty Earth Observatory of Columbia University, and Ana Navas-Acien and Anne Nigra from the Columbia Mailman School of Public Health.

The study was supported by NIEHS grants P42ES010349 and P30ES009089, and F31ES034284, and by NIH/National Institute of Dental & Craniofacial Research grant DP5OD031849.

The authors declare that they have no known competing financial interests.

Columbia University Mailman School of Public Health

Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the fourth largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.publichealth.columbia.edu

Journal Link: Environmental Research